Fuel Control In Refueling

Arthur asked...

Hi Helmis, could you give us some information about the fuel controls needed in refueling operations. In one opportunity I saw how fuel start droping overwing during a pressure refueling...how it happens??....probably instruments misfunction on the plane…or human error by plane crew???.....does each tank have a safety pressure device that allows fuel exhaust when the tank is overfilled...or when the tank is completelly fueled the systems cut the inlet fuel from the refueler.

Engineer Helmi replied..
Arthur, where did u saw it happen? I just had an experience last week in Al Ain.

The fuel can overflow if automatic cut of function of fuel system failed to activate during refueling. It can be the maximum level sensor or fuel quantity processor failed to send a signal to refueling sitch to close the fuel valve.

Normally if it overflow, it is airplane system, it can be a human error if someone manually override the system and continually fill the tank which rarely happen. The refueler only pump the fuel to aircraft but the aircraft system that will stop the fuel flow when maximum or desired selected fuel quantity obtained.

Best regards